Abstract: One of a plurality of data display formats with different units of correlation data that are prepared in advance is automatically selected depending on the variation of the amount of data in terms of the number of items thereof. One of a plurality of display methods with different summarization levels that are prepared in advance is also automatically selected for information (about correlation data or individual events) regarding individual cells. Information about the correlation data and individual cells is then displayed. The amount of work required to repeat the operation of observing the correlation data as a whole and the detailed observation of a small amount of data is reduced in a method for visualizing correlation data concerning two events in a matrix format.